Flooding

Because The Virginia B. Fairbanks Art & Nature Park:100 Acres is located within a meander of the White River, flooding is a common event, and certain areas tend to flood more frequently.

Flooding occurs in the Park when there is heavy rainfall or extensive snow melt in the upstream region of the White River watershed. As increasing amounts of water flow through the watershed and into the river as runoff and groundwater, the level of the river rises and approaches bankfull stage (as indicated in the image on the left). When the level surpasses this point (also known as flood stage) water begins to spread throughout the Park.

As the level and speed of the river increase during a flood, erosion of the banks is accelerated as new portions come in contact with the water. The increased levels of sediment in the river are deposited in flood plains, as the flood waters are slowed down by plants and rough terrain. Looser, more sandy soils within 100 Acres are composed of sediment that have been left by previous floods.

As a result of collaboration with the USGS, the IMA now has set of inundation maps, which can be used to estimate the extent of flooding using a stream gauge installed in the Park. The hydrograph generated by the gauge reports the current level of the river and the corresponding map shows a simulation of the flooding that would occur, based on digital elevation models.

Hydrographs

In the image on the right, the USGS hydrograph shows the measurements taken by the stream gauge over a period of 60 days. The peaks tend to occur after big rainstorms or after rising temperatures cause snow to melt. Some of the biggest floods happen as snow melts throughout the watershed in late winter. It is important to note that the peak in stream height often comes significantly later than the peak in precipitation or snowmelt. This is because the water usually travels a long distance through the watershed, which is mostly agricultural. Also notice that between the peaks the level drops as low as four feet. At this point, the river is at about the same level as the water table, what is known as base flow. The water represented by the region that is highlighted in blue comes mostly from groundwater, while the additional water is runoff from surfaces like farms, roads and parking lots.

The height of the White River can be accessed through a hydrograph on the IMA Dashboard. The yellow and red regions within the chart indicate the action and flood stages as determined by the National Weather Service. Local weather service stations generate alerts to the public when river levels reach these stages at points that they monitor, based on their knowledge of how river height relates to hazardous road conditions in an area.